已知y=f（x）上一点（x1，y1），则在y=x直线上的点就为（y1，y1）。对应f（x）上点坐标即为（y1，f（y1）……依次类推，可以迭代出蛛网图形用来判断不动点是否稳定。模型为：x(t+1)=c*x(t)^2*(2-x(t)),其中c=25/16。(A point (x1, Y1) on the y=f (x) is known, and the point on the y=x line is (Y1, Y1). The point coordinates corresponding to f (x) are (Y1, f (Y1))...... By analogy, the cobweb graph can be iterated to judge whether the fixed point is stable or not. The model is: X (t+1) =c*x (T) ^2* (2-x (T)), where c=25/16.)